Immunisation provides both individual protection and community protection from vaccine-preventable diseases. This makes it a powerful public health measure used all over the world to protect populations from preventable diseases. 

For vaccines to have their optimal effect, a high proportion of the population needs to be immunised. High coverage and on-time immunisation benefits those who have been vaccinated and can also provide protection for people who are not able to be immunised due to their age or a specific health condition.